Judge whether the parent node's child nodes will be loaded asynchronously when the parent node is expanded.
Do not initialize or modify it, it is created by the zTree.
Default:false (the parent node which have no child nodes); true (the parent node which have child nodes or the leaf node)
true means: the node's child nodes will not be loaded asynchronously when the parent node is expanded.
false means: the node's child nodes will be loaded asynchronously when the parent node is expanded.
This attribute will not effect to 'reAsyncChildNodes()' method
var treeObj = $.fn.zTree.getZTreeObj("tree");
var sNodes = treeObj.getSelectedNodes();
if (sNodes.length > 0) {
var zAsync = sNodes[0].zAsync;
}